A brushed motor has been used for an air conditioner that drives an impeller for generating an air flow to rotate by a motor, however, a brushless motor is used in recent years. As a blower motor for HVAC has a high output, and it is necessary to take countermeasures against noise in a motor for an in-vehicle air conditioner. When a natural frequency of the motor corresponds to a frequency of vibration generated with rotation of the impeller, resonance occurs and vibration is increased, as a result, noise is generated.
In view of the above, a bearing housing and a metal adjusting member are arranged in a molding die to be insert molded or the adjusting member is outsert molded in a concave portion provided in the bearing housing, thereby performing adjustment by the adjusting member so that a natural frequency of a device mounting portion fixed to the bearing housing differs from a frequency of vibration propagated from the bearing housing and suppressing the resonance (Patent Literature 1: JP-A 2015-1202).